Tenney L., Davis Ph.D. - The Chemistry of Powder and Explosives(ru)

PERMISSIBLE EXPLOSIVES

351

The French also have permissible explosives containing both ammonium nitrate and nitroglycerin (gelatinized), with and without saltpeter. These are called Grisou-dynamites or Grisoutines.

	Grisou-	Grisou-	Grisou-	Grisou-
		dynamite-		dynamite-
	dynamite-		dynamite-
		roche		couche
	roche		couche
		salpetree		salp&re'e
Nitroglycerin	29.0	29.0	12.0	12.0
Collodion cotton	1.0	1.0	0.5	0.5
Ammonium nitrate.	70.0	65.0	87.5	82.5
Potassium nitrate. . .		5.0		5.0
The effect of ammonium nitrate in lowering the				temperature

of explosion of nitroglycerin mixtures is nicely illustrated by the data of Naoum27 who reports that guhr dynamite (75% actual nitroglycerin) gives a temperature of 2940°, a mixture of equal amounts of guhr dynamite and ammonium nitrate 2090°, and &• mixture of 1 part of guhr dynamite and 4 of ammonium nitrate 1468°.

In ammonium nitrate explosives in which the ingredients are not intimately incorporated as they are in the Favier explosives, but in which the granular particles retain their individual form, the velocity of detonation may be regulated by the size of the •nitrate grains. A relatively slow explosive for producing lump coal is made with coarse-grained ammonium nitrate, and a faster explosive for the procurement of coking coal is made with finegrained material.

The first explosives to be listed as permissible by the U. S. Bureau of Mines were certain Monobels and Carbonites, and Monobels are still among the most important of American permissibles. Monobels contain about 10% nitroglycerin, about 10% carbonaceous material, wood pulp, flour, sawdust, etc., by the physical properties of which the characteristics of the explosive are somewhat modified, and about 80% ammonium nitrate of which, however, a portion, say 10%, may be substituted by a volatile salt such as sodium chloride.

27 Op. cit., p. 403.

352 DYNAMITE AND OTHER HIGH EXPLOSIVES

In Europe the tendency is to use a smaller amount of nitroglycerin, say 4 to 6%, or, as in the Favier explosives, to omit it altogether. Ammonium nitrate permissible explosives which contain nitroglycerin may be divided broadly into two principal classes, those of low ammonium nitrate content in which the oxygen is balanced rather accurately against the carbonaceous material and which are cooled by the inclusion of salts, and those which have a high ammonium nitrate content but whose temperature of explosion is low because of an incomplete utilization of the oxygen by a relatively small amount of carbonaceous material. Explosives of the latter class are more popular in England and in Germany. Several examples of commercial explosives of each sort are listed in the following table.

			I	II	III	IV	V	VI	VII VIII
Ammonium nitrate			52.0	53.0	60.0	61.0	66.0	73.0	78.0	83.0
Potassium		nitrate	21.0					2.8	5.0	7.0
Sodium	nitrate			12.0	5.0	3.0
Barium	nitrate									2.0
Na or K		chloride			21.0	20.5	22.0	15.0	8.0 ...
Hydrated		ammonium
oxalate			16.0	19.0
Ammonium chloride			6.0
Cereal or wood meal				4.0	4.0	75	2.0	1.0	5.0	2.0
Glycerin						3.0
Powdered coal							4.0
Nitrotoluene					6.0	1.0
Dinitrotoluene								5.0
Trinitrotoluene				6.0						2.0
Nitroglycerin			5.0	5.0	4.0	4.0	4.0	3.2	4.0	4.0

The Carbonites which are permissible are straight dynamites whose temperatures of explosion are lowered by the excess of carbon which they contain. As a class they merge, through the Ammon-Carbonites, with the class of ammonium nitrate explosives. The Carbonites, have the disadvantage that they produce gases which contain carbon monoxide, and for that reason have largely given way for use in coal mines to ammonium nitrate permissibles which contain an excess of oxygen. Naoiim 2S reports the compositions and explosive characteristics of four German Carbonites as follows.

28 Op. dt., p.401.

			SPRENGEL EXPLOSIVES				353
				I	II	III	IV
Nitroglycerin				25.0	25.0	25.0	30.0
Potassium		nitrate		305	34.0
Sodium	nitrate				...	305	245
Barium	nitrate			4.0	1.0
Spent tan		bark meal		40.0	1.0
Meal					38.5	39.5	405
Potassium			dichromate	...	.. .	5.0	5.0
Sodium	carbonate			0.5	0.5
Heat of explosion, Cal./kg				576	506	536	602
Temperature of explosion				1874°	1561°	1666°	1639°
Velocity	of		detonation, meters/sec. .. .	2443	2700	3042	2472
Lead block			expansion	235 cc.	213 cc. 240 cc. 258 cc.

The salts which are most frequently used in permissible explosives are sodium chloride and potassium chloride, both of which are volatile (the potassium chloride more readily so), ammonium chlorideand ammonium sulfate, which decompose to form gases, and the hydrated salts, alum A12(S04)3'K2S04'24H20; ammonium alum A12 (804)3 • (NH4) 2864-24H20; chrome alum Cr2(S04)3-K2S04-24H20; aluminum sulfate A12(S04)3-18H20; ammonium oxalate (NH4)2C204-H20; blue vitriol CuS04'5H20; borax Na2B407 • 10H20; Epsom salt MgS04-7H20; Glauber's salt Na2S04-10H20; and gypsum CaS04-2H20, all of which give off water, while the ammonium salts among them yield other volatile products in addition. Hydrated sodium carbonate is not suitable for use because it attacks both ammonium nitrate and nitroglycerin.29

Sprengel Explosives

Explosives of a new type were introduced in 1871 by Hermann Sprengel, the inventor of the mercury high-vacuum pump, who patented30 a whole series of mining explosives which were prepared by mixing an oxidizing substance with a combustible one "in such proportions that their mutual oxidation and de-oxidation should be theoretically complete." The essential novelty of his invention lay in the fact that the materials were mixed just before the explosive was used, and the resultant explosive mixture was

29 C. G. Storm, "The Analysis of Permissible Explosives," V. S. Bur. Mines Bull. 96, Washington, 1916.

80 Brit. Pats. 921, 2642 (1871).

354 DYNAMITE AND OTHER HIGH EXPLOSIVES

fired by means of a blasting cap. Among the oxidizing agents which he mentioned were potassium chlorate, strong nitric acid, and liquid nitrogen dioxide; among the combustible materials nitrobenzene, nitronaphthalenc, carbon disulfide, petroleum, and picric acid.31 Strong nitric acid is an inconvenientand unpleasant material to handle. It can eat through the copper capsule of a blasting cap and cause the fulminate to explode. Yet several explosives containing it have been patented, Oxonite, for example, consisting of 58 parts of picric acid and 42 of fuming nitric acid, and Hellhoffite, 28 parts of nitrobenzene and 72 of nitric acid. These explosives are about as powerful as 70% dynamite, but are distinctly more sensitive to shock and to blows. Hellhoffite was sometimes absorbed on kieselguhr to form a plastic mass, but it still had the disadvantage that it was intensely corrosive and attacked paper, wood, and the common metals.

The peculiarities of the explosives recommended by Sprengel so set them apart from all others that they define a class; explosives which contain a large proportion of a liquid ingredient and which are mixed in situ immediately before use are now known as Sprengel explosives. They have had no success in England, for the reason that the mixing of the ingredients has been held to constitute manufacture within the meaning of the Explosives Act of 1875 and as such could be carried out lawfully only on licensed premises. Sprengel explosives have been used in the United States, in France, and in Italy, and were introduced into Siberia and China by American engineers when the first railroads were built in those countries. Rack-a-rock, patented by S. R. Divine,82 is particularly well known because it was used for blasting out Hell Gate Channel in New York Harbor. On October 10, 1885, 240,399 pounds of it, along with 42,331 pounds of dynamite, was exploded for that purpose in a single blast. It was prepared for use by adding 21 parts of nitrobenzene to 79 parts of potassium chlorate contained in water-tight copper cartridges.

81 Sprengel was aware	in 1871 that picric acid alone could be detonated
by means of fulminate	but realized also that more explosive force could

be had from it if it were mixed with an oxidizing agent. Picric acid alone

was evidently not used practically			as	an explosive until	after Turpin in
1886 had proposed it	as a	bursting charge for shells.
32 Brit. Pats. 5584,	5596	(1881);	1461	(1882); 5624, 5625	(1883).

LIQUID OXYGEN EXPLOSIVES

355

The Promethees, authorized in France under the name of explostfs 0 No. 8, are prepared by dipping cartridges of a compressed oxidizing mixture of potassium chlorate 80 to 95% and manganese dioxide 5 to 20% into a liquid prepared by mixing nitrobenzene, turpentine, and naphtha in the proportions 50/20/30 or 60/15/25. The most serious disadvantage of these explosives was an irregularity of behavior resulting from the circumstance that different cartridges absorbed different quantities of the combustible oil, generally between 8 and 13%, and that the absorp-

tion was uneven and sometimes caused incomplete detonation.
Similar explosives are those of Kirsanov, a mixture of 90 parts of
turpentine and	10 of phenol absorbed by a mixture of 80 parts
of potassium	chlorate and 20 of manganese dioxide, and of

Fielder, a liquid containing 80 parts of nitrobenzene and 20 of turpentine absorbed by a mixture of 70 parts of potassium chlorate and 30 of potassium permanganate.

The Panclastites, proposed by Turpin in 1881, are made by mixing liquid nitrogen dioxide with such combustible liquids as carbon disulfide, nitrobenzene, nitrotoluene, or gasoline. They are very sensitive to shock and must be handled with the greatest caution after they have once been mixed. In the first World War the French used certain ones of them, under the name of Anilites, in small bombs which were dropped from airplanes for the purpose of destroying personnel. The two liquids were enclosed in separate compartments of the bomb, which therefore contained no explosive and was safe while the airplane was carrying it. When the bomb was released, a little propeller on its nose, actuated by the passage through the air, opened a valve which permitted the two liquids to mix in such fashion that the bomb was then filled with a powerful high explosive which was so sensitive that it needed no fuze but exploded immediately upon impact with the target.

Liquid Oxygen Explosives

Liquid oxygen explosives were invented in 1895 by Linde who had developed a successful machine for the liquefaction of gases. The Oxyliquits, as he called them, prepared by impregnating cartridges of porous combustible material with liquid .oxygen or liquid air are members of the general class of Sprengel explosives, and have the unusual advantage from the point of view of safety

356 DYNAMITE AND OTHER HIGH EXPLOSIVES

that they rapidly lose their explosiveness as they lose their liquid oxygen by evaporation. If they have failed to fire in a bore hole, the workmen need have no fear of going into the place with a pick or a drill after an hour or so has elapsed.

Liquid oxygen explosives often explode from flame or from the spurt of sparks from a miner's fuse, and frequently need no detonator, or, putting the matter otherwise, some of them are themselves satisfactory detonators. Like other detonating explosives, they may explode from shock. Liquid oxygen explosives made from carbonized cork and from kieselguhr mixed with petroleum were used in the blasting of the Simplon tunnel in 1899. The explosive which results when a cartridge of spongy metallic aluminum absorbs liquid oxygen is of theoretical interest because its explosion yields no gas; it yields only solid aluminum oxide and heat, much heat, which causes the extremely rapid gasification of the excess of liquid oxygen and it is this which produces the explosive effect. Lampblack is the absorbent most commonly used in this country.

Liquid oxygen explosives were at first made up from liquid air more or less self-enriched by standing, the nitrogen (b.p. —195°) evaporating faster than the oxygen (b.p. —183°), but it was later shown that much better results followed from the use of pure liquid oxygen. Rice reports 33 that explosives made from liquid oxygen and an absorbent of crude oil on kieselguhr mixed with lampblack or wood pulp and enclosed in a cheesecloth bag within a corrugated pasteboard insulator were 4 to 12% stronger than 40% straight nitroglycerin dynamite in the standard Bureau of Mines test with the ballistic pendulum. They had a velocity of detonation of about 3000 meters per second. They caused the ignition of fire damp and produced a flame which lasted for 7.125 milliseconds as compared with 0.342 for an average permissible explosive (no permissible producing a flame of more than 1 millisecond duration). The length of the flame was 21/2 times that of the flame of the average permissible. In the Trauzl lead block an

explosive	made up from		a liquid	air (i.e., a mixture of	liquid
33 George	S. Rice,	"Development of Liquid Oxygen Explosives			during
the War," U. S. Bur.		Mines	Tech. Paper	243, Washington, 1920, pp.	14-16.

Also, S. P. Howell, J. W. Paul, and J. L. Sherrick, "Progress of Investigations on Liquid Oxygen Explosives," U. S. Bur. Mines Tech. Paper 294, Washington, 1923, pp. 33, 35, 51.

CHLORATE AND PERCHLORATE EXPLOSIVES

357

oxygen and liquid nitrogen) containing 33% of oxygen gave no explosion; with 40% oxygen an enlargement of 9 cc.; with 50% 80 cc., with 55% 147 cc.; and with 98% oxygen an enlargement of 384 cc., about 20% greater than the enlargement produced by 60% straight dynamite. The higher temperatures of explosion of the liquid oxygen explosives cause them to give higher results in the Trauzl test than correspond to their actual explosive power.

Liquid oxygen explosives are used in this country for open-cut mining or strip mining, not underground, and are generally prepared near the place where they are to be used. The cartridges are commonly left in the "soaking box" for 30 minutes, and on occasions have been transported in this box for several miles.

One of the most serious faults of liquid oxygen explosives is the ease with which they inflame and the rapidity with which they burn, amounting practically and in the majority of cases to their exploding from fire. Denues3* has found that treatment of

the	granular carbonaceous absorbent with an aqueous solution
of	phosphoric acid results in an explosive which is non-inflam-

mable by cigarettes, matches, and other igniting agents. Monoand diammonium phosphate, ammonium chloride, and phosphoric acid were found to be suitable for fireproofing the canvas wrappers. Liquid oxygen explosives made up from the fireproofed absorbent are still capable of being detonated by a blasting cap. Their strength, velocity of detonation, and length of life after impregnation are slightly but not significantly shorter than those of explosives made up from ordinary non-fireproofed absorbents containing the same amount of moisture.

Chlorate and Perchlorate Explosives

The history of chlorate explosives goes back as far as 1788 when Berthollet attempted to make a new and more powerful gunpowder by incorporating in a stamp mill a mixture of potassium chlorate with sulfur and charcoal. He used the materials in the proportion 6/1/1. A party, had been organized to witness the manufacture, M. and Mme. Lavoisier, Berthollet, the Commissaire M. de Chevraud and his daughter, the engineer M. Lefort, and others. The mill was started, and the party went away for

34 A. R. T. Denues, "Fire Retardant Treatments of Liquid Oxygen Explosives," U. S. Bur. Mines Bull. 429, Washington, 1940.

358 DYNAMITE AND OTHER HIGH EXPLOSIVES

breakfast. Lefort and Mile, de Chevraud were the first to return. The material exploded, throwing them to a considerable distance and causing such injuries that they both died within a few minutes. In 1849 the problem of chlorate gunpowder was again attacked by Augendre vho invented a white powder made from potassium chlorate 4 parts, cane sugar 1 part, and potassium ferrocyanide 1 part. However, no satisfactory propellent powder for use in guns has yet been made from chlorate. Chlorate powders are used in toy salutes, maroons, etc,, where a sharp explosion accompanied by noise is desired, and chlorate is used in primer compositions and in practical high explosives of the Sprengel type (described above) and in the Cheddites and Silesia explosives.

Many chlorate mixtures, particularly those which contain sulfur, sulfides, and picric acid, are extremely sensitive to blows and to friction. In the Street explosives, later called Cheddites because they were manufactured at Chedde in France, the chlorate is phlegmatized by means of castor oil, a substance which appears to have remarkable powers in this respect. The French Commission des Substances Explosives in 1897 commenced its first investigation of these explosives by a study of those which are listed below, and concluded35 that their sensitivity to shock is

	I	II	III
Potassium chlorate	75.0	74.6	80.0
Picronitronaphthalene	20.0
Nitronaphthalene		5.5	12.0
Starch		14.9
Castor oil	5.0	5.0	8.0

less than that of No. 1 dynamite (75% guhr dynamite) and that when exploded by a fulminate cap they show a considerable brisance which however is less than that of dynamite. Later studies showed that the Cheddites had slightly more force than No. 1 dynamite, although they were markedly less brisant because of their lower velocity of detonation. After further experimentation four Cheddites were approved for manufacture in France, but the output of the Poudrerie de Vonges where they were made consisted principally of Cheddites No. 1 and No. 4.

35 Mem. Poudres, 9, 144 (1897-1898); 11,22 (1901); 12, 117, 122 (19031904); 13, 144, 282 (1905-1906); IS, 135 (1909-1910); 16,66(1911-1912).

CHLORATE AND PERCHLORATE			EXPLOSIVES	359
	ONo. 1	ONo. 1	ONo. 2
			Formula	0 No. 5
	Formula	Formula	60 bis M	Cheddite
	41	60 bis	Cheddite	No. 1
			No. 4
Potassium chlorate	80	80	79
Sodium chlorate			1	79
Nitronaphthalene	12	13
Dinitrotoluene . . :		2	15	16
Castor oil	8	5	5	5

The Cheddites are manufactured by melting the nitro compounds in the castor oil at 80°, adding little by little the pul- vr-ized chlorate dried and still warm, and mixing thoroughly. The mixture is emptied out onto a table, and rolled to a thin layer which hardens on cooling and breaks up under the roller and is then sifted and screened.

Sodium chlorate contains more oxygen than potassium chlorate, but has the disadvantage of being hygroscopic. Neither salt ought to be used in mixtures which contain ammonium nitrate or ammonium perchlorate, for double decomposition might occur with the formation of dangerous ammonium chlorate. Potassium chlorate is one of the chlorates least soluble in water, potassium perchlorate one of the least soluble of the perchlorates. The latter salt is practically insoluble in alcohol. The perchlorates are intrinsically more stable and less reactive than the chlorates, and are much safer in contact with combustible substances. Unlike the chlorates they are not decomposed by hydrochloric acid, and they do not yield an explosive gas when warmed with concentrated sulfuric acid. The perchlorates require a higher temperature for their decomposition than do the corresponding chlorates.

	SOLUBILITY: VABTS PER 100 PARTS OF WATER
		KC1O,	NaClO,	KC1O«	NH.CIO,
At	0°	3.3	82.	0.7	12.4
At	100°	56.	204.	18.7	882

Mixtures of aromatic nitro compounds with chlorate are dangerously sensitive unless they are phlegmatized with castor oil or a similar material, but there are other substances, such as

360 DYNAMITE AND OTHER HIGH EXPLOSIVES

rosin, animal and vegetable oils, and petroleum products, which give mixtures which are not unduly sensitive to shock and friction and may be handled with reasonable safety. Some of these, such as Pyrodialyte 38 and the Steelites,37 were studied by the Commission des Substances Explosives. The former consisted of 85 parts of potassium chlorate and 15 of rosin, 2 parts of alcohol being used during the incorporation. The latter, invented by Everard Steele of Chester, England, contained an oxidized rosin (residee in French) which was made by treating a mixture of 90 parts of colophony and 10 of starch with 42 Be nitric acid. After washing, drying, and powdering, the residee was mixed with powdered potassium chlorate, moistened with methyl alcohol, warmed, and stirred gently while the alcohol was evaporated. Colliery SteeUte

	STEELITE	STEELITE	STEELITE	COLLIERY
	No. 3	No. 5	No. 7	STEELITE
Potassium chlorate	75	8353	87.50	72.5-75.5
Residee	25	16.67	1250	23.5-265
Aluminum		5.00	...	...
Castor oil			0.5-1.0
Moisture			0-1
passed the Woolwich test for safety		explosives	and was formerly

on the British permitted list but failed in the Rotherham test. In Germany the Silesia explosives have been used to some extent. Silesia No. 4 consists of 80 parts of potassium chlorate and 20 of rosin, and Silesia IV 22, 70 parts of potassium chlorate, 8 of rosin, and 22 of sodium chloride, is cooled by the addition of the volatile salt and is on the permissible list.

The Sebomites3* invented by Eugene Louis, contained animal fat which was solid at ordinary temperature, and were inferior to

the Cheddites in their ability to transmit detonation. Explosifs			P
(potasse) and S (soude)39 and the Minelites*0 containing		petro-
leum hydrocarbons, were studied	in considerable detail by	Dau-
triche, some of whose results for	velocities of detonation are		re-

ported in the table on pages 362-363 where they are compared with

**Mem. Poudres, 11, 53 (1901).

Wlbid., 15, 181 (1909-1910).

38/bid., 13, 280 (1905-1906); IS, 137 (1909-1910). wibid., 15, 212 (1909-1910).

*<>ibid., 16, 224 (1911-1912).